Question

我有一个简单的textarea：

<textarea rows="10%" cols="100%" id="myTextArea">

每当我点击一个按钮时，我都有一个改变textarea值的函数。问题是我失去了旧值的旧价值。有办法保留所有这些吗？

function changeTextAreaValue1(){
    document.getElementById("myTextArea").value = "value1";
}
function changeTextAreaValue2(){
    document.getElementById("myTextArea").value = "value2";
}
changeTextAreaValue1();
changeTextAreaValue2();

我用这个简单的jsfiddle来说明：https://jsfiddle.net/syLuLob0/201/

提前谢谢

Answer 1

function changeTextAreaValue1(){
    document.getElementById("myTextArea").value = "value1";
}
function changeTextAreaValue2(){
    var oldVal = document.getElementById("myTextArea").value;
    document.getElementById("myTextArea").value = oldVal +"value2";
}
changeTextAreaValue1();
changeTextAreaValue2();



<textarea rows="10%" cols="100%" id="myTextArea"></textarea>

Demo

Answer 2

因为您要替换文本，所以需要连接到现有文本。

var ele = document.getElementById("myTextArea");

function changeTextAreaValue1(){
    ele.value += "value1"; // See the +
}
function changeTextAreaValue2(){
    ele.value += "value2";
}
changeTextAreaValue1();
changeTextAreaValue2();

Answer 3

var el = document.getElementById("myTextArea"),
    previousValue;

function changeTextAreaValue (val) {
    previousValue = el.value;
    el.value = val;
}

changeTextAreaValue("hello");
changeTextAreaValue("world");

// previousVar is now "hello"

如何更改textarea的旧价值后更新它的价值？

3 个答案: